Q&A #409

Addition reversal problems

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From: Gail (for Teacher2Teacher Service)
Date: Jul 15, 1998 at 12:22:39
Subject: Re: Addition reversal problems

I would use unit blocks (ones, tens and hundreds blocks) to help the
student understand that where the digits are in a number makes a difference
in how much they are worth.  If the student is adding 3 tens and 6 ones, and
2 tens and 4 ones, s/he can manually put the two groups together, and then
note how many are in each place value group.

If you give the student a grid to record the problem, with columns labeled
hundreds     tens     ones   they will have a way of recording their sums as
they work.  Giving them a set of problems to solve this way, and discussing
what happens each time, is important in assisting them in understanding.

Also, be sure to give them some problems that don't require regrouping the
ones digit, too.  Let them "discover" what happens when numbers are added.
When they add and get an incorrect sum, model that sum, and let them
determine why it couldn't be correct.

-Gail, for the Teacher2Teacher service

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